title: Effect of various forms of physical training on the autonomic nervous system activity in patients with acute myocardial infarction.
abstract: BACKGROUND
  A shift in the dynamic autonomic nervous system (ANS) balance towards sympathetic activity in patients with acute myocardial infarction (AMI) predisposes them to life-threatening ventricular arrhythmias. Improvement of unfavourable changes in ANS can be expected in such patients as a result of physical training. A beneficial shift in ANS balance towards parasympathetic activity could be confirmed by demonstrating increased baroreceptor reflex sensitivity (BRS) as well as favourable changes in heart rate variability (HRV) parameters.
  
  
  OBJECTIVE
  To analyse the effect of different forms of physical training on ANS activity in patients with AMI after hospital discharge.
  
  
  METHODS
  The study included 38 patients with AMI (aged 59 ± 8 years) subjected to 2-month exercise training. Group 1 (n = 19)underwent 3-week supervised in-hospital cardiac rehabilitation followed by 5-week home-based training, and Group 2 (n = 19) underwent 8-week home-based training. BRS and HRV were determined based on a 10-min recording of systolic arterial pressure and the cardiac cycle. Measurements were performed one day before discharge (R1) and after 2 months of training (R2).
  
  
  RESULTS
  A significant increase in the mean values of TP (total power), HF (high frequency power), rMSSD (square root of the mean of the squared differences between successive R-R intervals), and pNN50 (proportion of differences between successive R-R intervals that are greater than 50 ms) was observed in the overall study group, along with trends for higher SDNN (standard deviation of the mean of sinus rhythm R-R intervals) and HFnu (normalised HF power), and for lower LFnu (normalised LF power). Additionally, a significant increase in BRS (from 2.2 ± 0.6 to 5.1 ± 2.2 ms/mm Hg, p = 0.01) was found in patients with baseline BRS ≤ 3 ms/mm Hg. A significant increase in rMSSD, pNN50, HF and HFnu, as well as a decrease in LFnu and LF/HF (LF to HF ratio) was observed in Group 1. In contrast, a significant increase in BRS was noted in Group 2.
  
  
  CONCLUSIONS
  Various forms of 2-month physical training led to a favourable shift in autonomic balance towards parasympathetic activity. Our findings suggest a clinically important effect of physical activity in patients after AMI.
authors.affiliation: Department of Cardiology and Electrotherapy, Medical University of Gdansk, Poland. ludwik@gumed.edu.pl
authors.forename: Ludmiła
authors.initials: L
authors.lastname: Daniłowicz-Szymanowicz
authors.forename: Monika
authors.initials: M
authors.lastname: Figura-Chmielewska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Ratkowski
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Raczak
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D015444:Exercise; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology* / Q000534:rehabilitation*; D016896:Treatment Outcome